HEI ignition system was required with the hard to ignite lean mixtures during the smog era.
Used on a pre-smog era with fairly rich easily ignited mixtures it will burn off the mixture too fast compared to the point type style ignition system, making the engine ping, with the same timing settings.
It can be made to work well on these engines too, with a fairly amount of tuning.
In my opinion it´s not worth it.
I did some extensive testing on this issue a couple of years ago, but them again, every new generation have to invent the wheel for themselvs, so to speak
Remember that the RAIV and 455SD engines were pretty strong runners with points style ignition.